This invention relates to pipe cutting, and more particularly to a system particularly adapting to cutting large diameter pipe.
It is frequently desirable to cut large diameter heavy duty pipe for repair or replacement of sections of a pipe or components connected to the pipe. Such large diameter pipe is typically twenty-five centimeters and more in diameter and may be of larger diameter such as thirty centimeters diameter, forty centimeters diameter, and more. Such large diameter pipes frequently have wall thicknesses of one centimeter or more, and the cutting of a section of such pipe is an arduous task. For example, cutting of a ninety centimeter outer diameter steam line that has a five centimeter wall thickness may take several days using conventional technology.
In accordance with one aspect of the invention, there is provided a pipe cutting system that includes an annular pipe encircling band member with parallel edge surfaces for encircling the pipe to be cut, releasable structure for securing the band member in pipe encircling configuration, and structure for spacing the edge surfaces of the band from the outer surface of the pipe. A carriage assembly includes two pairs of opposed spaced guide members for engaging opposed edges of the band and providing stable guidance of the carriage assembly around the pipe and structure for fixedly mounting a cutting tool on the carriage assembly. The cutting tool assembly is secured to the carriage assembly for movement relative to the pipe, preferably about a pivot axis parallel to the axis of the pipe, and includes a drive motor, a manual motor control, and a cutter disc coupled to the drive motor and adapted to be driven in rotation by the drive motor in response to the manual motor control.
Preferably, the band member in a flexible metal strip with parallel guide surfaces at its opposed edges that extend along its length, the spacer structure spaces the track strip edges at least about two millimeters from the outer surface of the pipe, and each guide member is a rotatable wheel with a groove that engages a corresponding one of the guide edges of the band member.
In a particular embodiment, the carriage assembly includes two subassemblies coupled together in articulated relation, structure for fixing the subassemblies in a particular angularly offset relation corresponding to the diameter of the pipe to be cut, and each subassembly includes a body portion and a pair of spaced depending bracket members, each of which carries a grooved guide wheel. The cutter disc has a diameter of at least twenty centimeters and the drive motor rotates the cutter disc at a speed of at least three thousand rpm.
The system allows more rapid and more accurate cutting of pipe end surfaces than prior art pipe cutting technology with little or no heat affected zone (HAZ).